At this point there are three FPV specific goggle solutions that will absolutely work with the HDMI output from the P3 (and Inspire 1):
* HeadPlay HD goggles
* FatShark Dominator HD goggles
* Zeiss Cinemizer OLED goggles
The Dominator HD's are going to be superseded by a newer model in a 30 - 60 days.
The HeadPlays (which I use) are the lowest cost solution but are very bulky.
The Cinemizers are currently discontinued, not sure about a replacement.
(I have flown with each of the three goggles above and they all work well. The visual experience is slightly different between each type of goggles.)
In addition, there are several 720p goggles coming out from new vendors, as well as a new update of the FatShark Dominator V2,which might work, although the consensus is that it will not support the required 720p resolution even though the goggles do have an HDMI micro input.
If you are using the Nvidia Shield it is possible to use that tablet's HDMI output to mirror the app screen image.
In addition to the ability to provide a second video output, the HDMI board's video will not be subjected to processing delays from your tablet. This is very desirable when flying FPV.
:harry
